Copolymers



3,025,272 COPULYMERS Richard H. Martin, .lr., Springfield, Mass, assignor t Monsanto Chemical (Iornpany, 'St. Louis, Mo., a corporation of Delaware No Drawing. Filed July 31, 1959, Ser. No. 830,705 8 Claims. (Cl. zen-7m The present invention relates to novel vinyl chloride interpolymers and to methods for preparing same.

Vinyl chloride homopolymers are widely employed as a surface coating resin, as a wire insulation resin, and for diverse other purposes. A relatively recent development in the art has been the employment of vinyl chloride polymer insulated wires as underground electrical cables. The insulation on such underground cables must be able to withstand severe physical punishment and for maximum utility requires vinyl chloride polymers having physical properties superior to those of many of the presently commercially available vinyl chloride homopolymers. In particular, this development requires vinyl chloride polymers having a high tensile strength, a high 100% modulus and a high crush-resistance.

It is known that the physical properties of vinyl chloride homopolymers such as tensile strength, 100% modu- Ins and crush-resistance can be improved by preparing the polymer under such conditions that higher molecular weights are obtained. To obtainsuch higher molecular weights it has heretofore been necessary to lower the polymerization temperature or to reduce the concentration of free radical generating polymerization initiator employed or both. Such modifications of the polymerization process increase the cost of preparing vinyl chloride homopolymers in that they lower the rate of polymerization and concomitantly the productive capacity of the equipment in which the polymer is prepared.

A method sometimes proposed for increasing the molecular weight of polymers is to incorporate a small quantity of a cross-linking monomer, i.e., a monomer containing two or more non-conjugated terminal ethylenic groups, in the monomer charge. This method has been used successfully with some polymer systems, but it is not generally applicable to the preparation of vinyl chloride polymers of high molecular weight. In particular, it is difiicult to find cross-linking monomers which will interpolymerize with vinyl chloride at satisfactory rates. Moreover, where interpolymers can be formed, they tend to be quite heterogeneous in composition and in most cases the interpolymer contains a highly gelled fraction which is insoluble in most solvents for the vinyl chloride interpolymer. Such interpolymers, because of their heterogeneity and insoluble gel fraction, can not be employed in surface coating compositions.

It is an object of this invention to provide vinyl chloride polymers having improved physical properties.

Another object of this invention is to provide a process for preparing vinyl chloride polymers of improved physical properties, which process can be carried out in conventional polymerization equipment.

A further object of this invention is to provide a vinyl chloride polymerization process which, with no sacrifice in the rate of polymerization, yields vinyl chloride polymers of improved physical properties.

Other objects and advantages of this invention will be apparent from the following detailed description thereof.

It has been discovered that vinyl chloride polymers of improved physical properties, as compared with vinyl chloride homopolymers prepared under otherwise identical conditions, can be obtained by interpolymerizing minute but critical quantities of an allyl ether-allyl ester of a ice hydroxy carboxylic acid with vinyl chloride. Such improved vinyl chloride interpolymers contain 0003-030 weight percent of the allyl ether-allyl ester of the hydroxy carboxylic acid with the balance of the interpolymer being vinyl chloride. The vinyl chloride interpolymers of improved physical properties are obtained at rates of polymerization which are fully equivalent to those obtained in the homopolymerization of vinyl chloride.

As noted earlier herein, it is known that the physical properties of vinyl chloride polymers such as tensile strength, modulus and crush-resistance are improved as the molecular weight of the vinyl chloride polymer is increased. This is true not only for vinyl chloride polymers per se, but also for formulated vinyl chloride polymer compositions containing plasticizers, pigments, fillers and other conventional polymer compounding ingredients. Since the precision of molecular weight determinations is much higher than the precision of determinations of tensile strength, 100% modulus and crushresistance, the comparison of polymer properties in the subsequent examples is based primarily upon polymer molecular weights, such molecular Weights being expressed in terms of the specific viscosities of the polymers. All of the specific viscosities reported herein are determined on 0.4 weight percent solutions of the polymer in cyclohexanone at 25 :0.05 C. The precision of the reported values is 10.002. The formula employed for calculating specific viscosities is set forth below:

Specific Viscosity Soluti0n Viscosity-Solvent. Viscosity Solvent Viscosity The following examples are set forth to illustrate more clearly the principle and practice of this invention to those skilled in the art. All parts are by weight.

EXAMPLE I Part A A vinyl chloride homopolymer is prepared in a stirred autoclave employing the suspension polymerization system set forth below:

Equimolar interpolymer of vinyl acetate and malelc anhydride.

The polymerization is carried out at 51 C. and is completed in about 16 hours. The vinyl chloride homopolymer has a specific viscosity of 0.51.

Part B An interpolymer consisting of 99.98 weight percent of vinyl chloride and 0.02 weight percent of allyl-beta-allyloxypropionate is prepared by the procedure of Part A above and has a specific viscosity of about 0.55. In comparing this specific viscosity value with the specific viscosity of the vinyl chloride homopolymer prepared in Part A above, it will be noted that, although the interpolymer contains only 0.02 weight percent of allyl-betaallyloxypropionate, the specific viscosity of the resulting interpolymer is about 8% higher than the value obtained with the vinyl chloride homopolymer.

Part C The vinyl chloride-allyl-beta-allyloxypropionate polymer of Part B is compounded into the wire coating formulation set forth below:

Component: Parts by weight Resin 100 Di(2-ethylhexyl)phthalate 42 Secondary plasticizer 1 22 Clay 20 Calcium carbonate Stabilizer 8 Lubricant 1 1 Hydrocarbon type.

The resulting formulation has a tensile strength of about 2600 p.s.i. and 100% modulus of about 1800 p.s.i. By way of contrast, when the vinyl chloride homopolymer of Example I, Part A is substituted for the vinyl chloride-allyl-beta-allyloxypropionate interpolymer, the resulting formulation has a tensile strength and 100% modulus approximately 100 points lower.

EXAMPLES I*IV Example I, Part B, is repeated except that the allylbeta-allyloxypropionate contained in the polymerization system is replaced with, respectively, allyl-allyloxyacetate, allyl-o-allyloxybenzoate (the allyl ether-allyl ester of salicylic acid), allyl-p-allyloxybenzoate and allylgamma-allyloxybutanoate. The physical properties of the resulting interpolymers correspond to those of the interpolymer obtained in Example I Part B.

EXAMPLE VI An interpolymer consisting of 99.97 weight percent of vinyl chloride and 0.03 weight percent of allyl-3,4- diallyloxybenzoate is prepared by the procedure of Example I, Part B and has a specific viscosity of about 0.60.

EXAMPLES VII-XI Five vinyl chloride-allyl-beta-allyloxypropionate polymers containing varying quantites of allyl-beta-allyloxypropionate are prepared under identical polymerization conditions following the procedure of Example I, Part B. The composition of the interpolymers and the specific viscosities thereof are set forth in Table I.

As seen from the above table, each of the interpolymers containing allyl-beta-allyloxypropionate has a higher specific viscosity than the control vinyl chloride homopolymer. Each of the allyl-beta-allyloxypropionate containing interpolymers also has a higher tensile strength and 100% modulus than the control vinyl chloride homopolymer. In addition, each of the interpolymers is free of gels and is completely soluble in such solvents as cyclohexanone and nitrobenzene. Accordingly, the interpolymers are well suited for use in paints and other surface coating compositions.

The interpolymers of this invention are binary interpolymers consisting of vinyl chloride and an allyl etherallyl ester of a hydroxy carboxylic acid, which for the sake of brevity will sometimes be referred to simply as the polyallyl compound. The polyallyl compounds which can be employed in the practice of this invention can be aliphatic, aromatic or heterocyclic in nature and are characterized by (1) containing at least one allyloxy group of the formula:

R OH2=(IJCHZO- where R is selected from the group conssiting of a hydrogen atom and a methyl radical, (2) containing at least one carballyloxy group of the formula:

R! CHF-OHr-O-Jiwhere R is selected from the group consisting of a hydrogen atom and a methyl radical, (3) the number of allyloxy and carballyloxy groups from 1) and (2) totaling not more than three, and -(4) containing no polymerizable terminal ethylenic groups other than those specified in (1) and (2).

Typical examples of suitable polyallyl compounds inculde allyl (or methallyl) ether-allyl (or methallyl) esters of monohydroxy monocarboxylic acids, e.g., hydroxyacetic acid, hydroxyisobutyric acid, 2-hydroxynico tinic acid, etc.; polyhydroxy monocarboxylic acids, e.g., gallic acid, etc.; and monohydroxy polycarboxylic acids, e.g., 3-hydroxyadipic acid, etc. Such polyallyl compounds can be prepared by classical methods and certain of these compounds are commercially available.

The proportions of vinyl chloride and polyallyl compound included in the interpolymers will depend upon the number of allyl (or methallyl) groups included in the polyallyl compound. When the polyallyl compound contains 2 allyl (or methallyl) groups, the interpolymer will consist of 99.7099.99 and preferably 99.85-99.98 weight percent of vinyl chloride and, correspondingly, 0.30-0.01 and preferably 0.15-0.02 weight percent of the polyallyl compound. When the polyallyl compound contains 3 allyl (or methallyl) groups, the interpolymer will consist of 99.9599.997 and preferably 99.96-99.995 weight percent of vinyl chloride and, correspondingly, 0.05-0.003 and preferably 0.040.005 weight percent of the polyallyl compound.

The interpolymers of the invention are preferably prepared by the Well-known suspension polymerization process in which the monomers are dispersed as small droplets in water and polymerized therein. Although a watersoluble interpolymer of vinyl acetate and maleic anhydride has been employed as the suspending agent in the examples herein presented, other known suspending agents such as gelatin, protective colloids, etc. may be employed if desired. The polymerizations are carried out at temperatures in the range of 3070 C. in the presence of free radical generating polymerization initiators such as lauroyl peroxide, benzoyl peroxide, etc.

The interpolymers of this invention have higher molecular weights and better physical properties than corresponding vinyl chloride homopolymers prepared under identical polymerization conditions. Thus, the process of this invention makes possible the attainment of a superior product at no increase in cost. Alternatively, interpolymers of this invention having equivalent physical properties to vinyl chloride homopolymers can be prepared at higher polymerization temperatures. Polymerizing the interpolymers at higher temperatures increases the rate of polymerization and raises the productive capacity of the polymerization vessel in which the reaction is carried out. Thus, the interpolymers of this invention make possible the attainment of a higher productive capacity per unit of capital investment. In general, the productive capacity of a polymerization vessel for the interpolymers of this invention is approximately 30% higher than the productive capacity of the same vessel for a vinyl chloride homopolymer, both of said polymers being polymerized under conditions which give identical molecular weights.

The interpolymers of this invention may be used interchangeably with vinyl chloride homopolymers in virtually all industrial applications. The interpolymers are particularly suitable for use in the insulation of electric wire and particularly for electric wire that is to be employed as underground cable.

The above descriptions and particularly the examples are set forth by way of illustration only. Many other variations and modifications thereof will be obvious to those skilled in the art and can be made without departing from the spirit and scope of the invention herein disclosed.

What is claimed is:

l. A resinous interpolymer selected from the group consisting of (a) a binary interpolymer of 99.70-99.99 weight percent of vinyl chloride and, correspondingly, 0.30-0.01 weight percent of a polyallyl compound which is an allyl ether-allyl ester of a hydroxy carboxylic acid of the group consisting of aliphatic, aromatic and heterocyclic hydroxy carboxylic acids which compound contains (1), as the ether moiety, one allyloxy group of the formula:

l CH2=C-CH2O- where R is selected from the group consisting of a hydrogen atom and a methyl group, (2), as the ester moiety, one carballyloxy group of the formula:

where R is selected from the group consisting of a hydrogen atom and a methyl radical, and (3) no polymerizable terminal ethylenic groups other than those specified in (1) and (2), and (b) a binary interpolymer of 99.95-99.997 weight percent of vinyl chloride and, correspondingly, 0.05-0.003 weight percent of 'a polyallyl compound which is an allyl ether-allyl ester of a hydroxy carboxylic acid of the group consisting of aliphatic, aromatic' and heterocyclic hydroxy carboxylic acids which compound contains (1), as the ether moiety, at least one allyloxy group of the formula:

where R is selected from the group consisting of a hydrogen atom and a methyl group, (2), as the ester moiety, at least one carballyloxy group of the formula:

I ll

where R is selected from the group consisting of a hydrogen atom and a methyl radical, (3) the number of allyloxy and carballyloxy groups from (1) and (2) totaling three, and (4) no polymerizable terminal ethylenic groups other than those specified in (l) and (2).

2. A resinous interpolymer selected from the group consisting of (a) a binary interpolymer of 99.85-99.98 weight percent of vinyl chloride and, correspondingly, 0.l50.02 weight percentof a polyallyl compound which is an allyl ether-allyl ester of a hydroxy carboxylic acid of the group consisting of aliphatic, aromatic and heterocyclic hydroxy carboxylic acids which compound contains (1), as the ether moiety, one allyloxy group of the formula:

l CH2=C-CH2-O where R is selected from the group consisting of a hydrogen atom and a methyl group, (2), as the ester moiety, one carballyloxy group of the formula:

l ll CHn=C-CHa-O--C where R is selected from the group consisting of a hydrogen atom and a methyl radical, and (3) no polymerizable terminal ethylenic groups other than those specified in (1) and (2), and (b) a binary interpolymer of 99.96-99.995 weight percent of vinyl chloride, and, correspondingly, 0.04-0.005 weight percent of a polyallyl compound which is an allyl ether-allyl ester of a hydroxy carboxylic acid of the group consisting of aliphatic, aromatic and heterocyclic hydroxy carboxylic acids which compound contains (1), as the ether moiety, at least one allyloxy group of the formula:

R OI-IF('J-CH2O where R is selected from the group consisting of a hydrogen atom and a methyl group, (2), as the ester moiety, at least one carballyloxy group of the formula:

0 CH2=( 3-CHzO-( where R is selected from the group consisting of a hydrogen atom and a methl radical, (3) the number of allyloxy and carballyloxy groups from (1) and (2) totaling three, and (4) no polymerizable terminal ethylenic groups other than those specified in (1) and (2).

3. A suspension polymerization process for preparing a resinous interpolymer of a monomer mixture consisting of vinyl chloride and a polyallyl compound, which process comprises dispersing the monomers as droplets in an aqueous medium containing therein a suspending agent and polymerizing the monomers at a temperature of 3070 C. in the presence of a free radical generating initiator; said monomer mixture being selected from the group consisting of (a) a binary mixture of 99.70-99.99 Weight percent of vinyl chloride and, correspondingly, 0.30-0.01 weight percent of a polyallyl compound which is an allyl ether-allyl ester of a hydroxy carboxylic acid of the group consisting of aliphatic, aromatic and heterocyclic hydroxy carboxylic acids which compound contains (1), as the ether moiety, one allyloxy group of the formula:

R CH2=(\]-CH2O where R is selected from the group consisting of a hydrogen atom and a methyl group, (2), as the ester moiety, one carballyloxy group of the formula:

RI CHFC l-CH2O(%- where R is selected from the group consisting of a hydrogen atom and a methyl radical, and (3) no polymerizable terminal ethylenic groups other than those specified in (l) and (2), and (b) a binary mixture of 99.95-99.997 weight percent of vinyl chloride and, correspondingly, 0.050.003 weight percent of a polyallyl compound which is an allyl ether-allyl ester of a hydroxy carboxylic acid of the group consisting of aliphatic, aromatic and heterocyclic hydroxy carboxylic acids Which compound contains (1), as the ether moiety, at least one allyloxy group of the formula:

l CH2=COH2O where R is selected from the group consisting of a hydrogen atom and a methyl group, (2), as the ester moiety, at least one carballyloxy group of the formula:

where R is selected from the group consisting of a hydrogen atom and a methyl radical, (3) the number of allyloxy and carballyloxy groups from (1) and (2) totaling three, and (4) no polymerizable terminal ethylenic groups other than those specified in (l) and (2).

4. A suspension polymerization process for preparing a resinous interpolymer of a monomer mixture consisting of vinyl chloride and a polyallyl compound, which process comprises dispersing the monomers as droplets in an aqueous medium containing therein a suspending agent and polymerizing the monomers at a temperature of 30-70 C. in the presence of a free radical generating initiator; said monomer mixture being selected from the group consisting of (a) a binary mixture of 99.85-99.98 weight percent of vinyl chloride and, correspondingly, 0.15-0.02 weight percent of a polyallyl compound which is an allyl ether-allyl ester of a hydroxy carboxylic acid of the group consisting of aliphatic, aromatic and heterocyclic hydroxy carboxylic acids which compound contains (1), as the ether moiety, one allyloxy group of the formula:

where R is selected from the group consisting of a hydrogen atom and a methyl group, (2), as the ester moiety, one carballyloxy group of the formula:

where R is selected from the group consisting of a hydrogen atom and a methyl radical, and (3) no polymerizabie terminal ethylenic groups other than those specified in (1) and (2), and (b) a binary mixture of 99.96-99.995 weight percent of vinyl chloride and, correspondingly, 0.04-0.005 weight percent of a polyallyl compound which is an allyl ether-allyl ester of a hydroxy carboxylic acid of the group consisting of aliphatic, aromatic and heterocyclic hydroxy carboxylic acids which compound contains (1), as the ether moiety, at least one allyloxy group of the formula:

where R is selected from the group consisting of a hydrogen atom and a methyl group, (2), as the ester moiety, at least one carballyloxy group of the formula:

where R is selected from the group consisting of a hydrogen atom and a methyl radical, (3) the number of allyloxy and carballyloxy groups from (1) and (2) totaling three, and (4) no polymerizable terminal ethylenic groups other than those specified in (1) and (2).

5. An insulated electric wire comprising an electrical wire carrying an insulating coating of a resinous interpolymer selected from the group consisting of (a) a binary interpolymer of 99.70-99.99 weight percent of vinyl chloride and, correspondingly, 0.30-0.01 weight percent of a polyallyl compound which is an allyl ether-allyl ester of a hydroXy carboxylic acid of the group consisting of aliphatic, aromatic and heterocyclic hydroxy carboxylic acids which compound contains (1), as the ether moiety, one allyloxy group of the formula:

Where R is selected from the group consisting of a hydrogen atom and a methyl group, (2), as the ester moiety, one carballyloxy group of the formula:

CH:=( ]-CH2O( where R is selected from the group consisting of a hydrogen atom and a methyl radical, and (3) no polymerizable terminal ethylenic groups other than those specified in 1) and (2), and (b) a binary interpolymer of 99.95-99.997 weight percent of vinyl chloride and, correspondingly, 0.05-0.003 weight percent of a polyallyl compound which is an allyl ether-allyl ester of a hydroxy carboxylic acid of the group consisting of aliphatic, aromatic and heterocyclic hydroxy carboxylic acids which compound contains (1), as the ether moiety, at least one allyloxy group of the formula:

R CH:=1CHz-O where R is selected from the group consisting of a hydrogen atom and a methyl group, (2), as the ester moiety, at least one carballyloxy group of the formula:

R 0 '4. CH7CCH2O where R is selected from the group consisting of a hydrogen atom and a methyl radical, (3) the number of allyloxy and carballyloxy groups from (1) and (2) totaling three, and (4) no polymerizable terminal ethylenic groups other than those specified in 1) and (2).

6. A resinous interpolymer of monomers consisting of 99.85-9998 weight percent of vinyl chloride and, correspondingly, 0.15-0.02 weight percent of allyl-betaallyloxypropionate.

7. A resinous interpolymer of monomers consisting of 9985-9998 weight percent of vinyl chloride and, correspondingly, 0,150.02 weight percent of allyl-gammaallyloxybutanoate.

8. A resinous interpolymer of monomers consisting of 99.85-9998 Weight percent of vinyl chloride and, correspondingly, 0.15-0.02 weight percent of allyl-o-allyloxybenzoate.

References Cited in the file of this patent UNITED STATES PATENTS 2,202,846 Garvey June 4, 1940 2,437,508 DAlelio Mar. 9, 1948 2,448,246 Barker et al. Aug. 31, 1948 2,515,132 Milone July 11, 1950 2,898,244 Martin Aug. 4, 1959 

1. A RESINOUS INTERPOLYMER SELECTED FROM THE GROUP CONSISTING OF (A) A BINARY INTERPOLYMER OF 99.70-99.99 WEIGHT PERCENT OF VINYL CHLORIDE AND, CORRESPONDINGLY 0.30-0.01 WEIGHT PERCENT OF A POLYALLYL COMPOUND WHICH IS AN ALLYL ETHER-ALLYL ESTER OF A HYDROXY CARBOXYLIC ACID OF THE GROUP CONSISTING OF ALIPHATIC, AROMATIC AND HETEROCYCLIC HYDROXY CARBOXYLIC ACIDS WHICH COMPOUND CONTAINS (1) AS THE ETHER MOIETY, ONE ALLYLOXY GROUP OF THE FORMULA; 